Safety device for ski-boot coupling



June 20, 1967 A. PRONZATI 3,326,567

SAFETY DEVICE FOR SKI-BOOT COUPLING Filed Sept. 24, 19.65 I 2 Sheets-Sheet 1 2 INVENTOR June 20, 1967 A. PRONZATI SAFETY DEVICE FOR SKI-BOOT COUPLING 2 Sheets-Sheet 2 Filed Sept. 24, 1965 INVENTOR A11 [/10 ron z a. ti

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United States Patent O 3,326,567 SAFETY DEVICE FOR SKi-IEQOT COUPLING Attilio Pronzati, Vanzago, Milan, Italy Filed Sept. 24, 1965, Ser. No. 489,967 Claims priority, application Italy, Sept. 26, 1964, Patent 738,407; Dec. 15, 1964, 26,781/64; Sept. 15, 1965, 20,542/ 65 11 Claims. (Cl. 280-11315) Numerous safety devices for ski-boot coupling are known, all of which aiming to release the boot (and thence the skiers foot) from the ski, when stress on the coupling exceeds a given value, in order that transfer of stress to the skiers foot and leg be avoided.

Particularly, devices are known comprising a shaped plate retaining the boot and being coupled to the ski by a resilient lock and adapted to rotate about two axes, one of which is perpendicular to the ski plane and the other of which is normal to the former and the ski sides.

According to the latter devices, the above mentioned two axes cross in a link and the pivot, perpendicular to the ski plane and forming part of link itself, is exceedingly stressed; as a result, there will be an abnormal wear and a rapid falling out of use of the pivot.

In addition, according to such devices, the stress value suitable to release the plate from the resilient lock by causing it to rotate about the axis perpendicular to the ski plane is equal to that of the stress releasing the same from said lock and causing it to rotate about the axis perpendicular to the former.

It is instead appropriate that such values be different, and particularly that the stresses, causing said plate to rotate about the axis perpendicular to the ski plane and releasing the skiers foot from dangerous twists, be lower thm those in a direction perpendicular to the former and releasing the skiers foot, thus avoiding extreme longitudinal stresses (boot tip lifting).

It is therefore the object of the present invention to provide a safety device for ski-boot coupling, adapted to eliminate said drawbacks deriving from the known devices and showing the performances hereinabove disclosed.

More particularly, it is the object of the present invention to provide a safety device for ski-boot coupling, comprising, in combination, a base fitted with a pivot perpendicular to the ski plane, about which pivot a link block is rockingly mounted, said link block being crossed by a horizontal pin at right angles to said pivot and ski edges, and onto which and through parallel side fins a support member is rockable, said member carrying a plate, the end of which remote from the pivot carries a downward appendix, perpendicular to the ski plane, wherein a bore surrounded by an annular seating of a dissymmetrical section is formed, said seating being suitable to accommodate the projecting portion of a small ball under the adjustable resilient action of a spring; the dissymmetrical seating for the ball joint having at least two diametral horizontal regions with a reduced slope and a bottom region with a steep slope to effect the skiers foot release by smaller horizontally directed stresses (twist) and greater vertically directed stresses.

By way of non-restrictive example, the accompanying drawing diagrammatically shows some embodiments of the present invention, and in particular:

FIGURE 1 is a side view of the device embodying the invention;

FIGURE 2 is a plan view of the device of FIGURE 1;

FIGURE 3 is a side view of only the pivot vertical with the link block;

3,325,557 Patented June 20, 1967 FIGURE 4 is a plan view of the same and of the adjustable pressure ball;

FIGURE 5 is a perspective view of the plate alone;

FIGURES 6 and 7 show two structural details of a different embodiment;

FIGURE 8 is a side view of a third embodiment; and

FIGURES 9 and 10 are two details of the embodiment of FIGURE 8.

With particular reference to FIGURES 1 and 2, the device there shown comprises a base 1, integral with ski 2, on which a substantially cylindrical body 3, containing a small ball 4 the cap 4 of which frontally projects is secured, as well as a pivot 5 about which the block 6 rotates through its collar 7.

A support member 12 (shown in more detail in FIG- URE 5) is provided with parallel fins 9 enclosing block 6 with some clearance and is allowed to rotate relative to block 6 owing to pin 11 passing through fins 9 and block 6.

At the opposite end to the end carrying fins 9, said member 12 has an appendix 10, substantially at right angles to the ski plane 2, on the inner wall of which there is a bore 26 defined by a ring 23 integral with appendix 10 forming the seating wherein the projecting cap 4 of ball 4 is located. Secured on said support member 12 is a plate 8, the plan section of which is substantially trapezoidal shaped, and having a portion 8 at right angles to the ski and surrounding appendix 10 of member 12. On its outer face said portion 8' has a notch 15 intended for accommodating the boot tip, that is also retained by the sole fastener fins 13 and 14 parallel to the ski plane and by which plate 8 terminates. Said notch 15 is considerably wide and such as to minimize the specific pressure against the boot. Within the tubular body 3, containing ball 4, an externally threaded cylindrical bushing is slidably mounted; against the bottom of said bushing an end of a helical spring rests, whereas the other end of the spring operates on the small ball 4, the latter being retained by end 16 of the tubular body 3, the diameter of which is smaller than that of ball 4. A knurled ring 17 is internally provided with a spoke housing within thread of the cylindrical bushing, so that ring rotation in either directions defines bushing displacement in either directions and thence a greater or smaller compression of the spring operating on small ball 4; indices 18 and 18, integral with said bushing and sliding within slots 20 and 20', respectively, indicate the maximum or minimum or mean value for such compression, reference being made to numbers stamped onto the outer wall of the tubular body 3.

As seen from the assembly view of FIGURE 1, as well as from the structural details of FIGURES 3 and 4, the axes about which plate 8 and its support 12 can rotate respectively comprise pivot 5 and pin 11. The first axis is vertical and perpendicular to the ski plane, whereas the second axis is horizontal and thence at right angles to the former and to sides 21 and 22 of the ski.

The two mutually perpendicular axes 5 and 11 do not meet, but are only close to each other, thereby obtaining a compact and sturdy structure, while not subjecting pivot 5 to extreme stresses.

It is to be noted that the horizontal axis (pin 11) about which plate 8 can rotate, said plate being carried by support 12, is very close to the ski plane. As a result, the middle axis of the boot thrust against the device is higher than the same and the arc of the circle described by the boot tip is certainly over the dead center.

In the event of a rotation of plate 8 about pin axis 11 there will practically be no initial backward movement of the boot, i.e. of the skiers foot, backward movement that might be harmful.

On considering the coupling between small ball 4 and annular seating 23 of portion 10, it is seen that said seating (FIGURE 5) is internally shaped according to a substantially semitoric surface 25 having, however, in its region closer to ski 2 a curvature 25 the radius of which is less than that of the curvatures of the lateral regions 25".

Thus, stress required for causing small ball'to exit from the annular seating 23 is smaller than when plate 8 is urged to rotate about axis of pivot 5 normal to the ski plane and thence small ball 4 slides against one of regions 25", as to when plate 8 is urged to rotate about horizontal axis of pin 11 and thence small ball 4 slides against region 25 (the curvature of which is of a less radius).

In FIGURES 6 and 7 there are shown two structural modified members embodying a modification of the device. Within the cylindrical bushing there is slidably arranged a piston 30 (shown on an enlarged scale in FIG- URE 6), the head 33 of which projects from said tubular body 3.

Shank 31 of said piston 30 is inserted within a cylindrical helical spring, in turn contained within the bushing; one end of the spring rests against surface 32 of head 33 of the finger, while the other end rests against the bottom of the cylindrical threaded bushing.

Knurled ring 17 (FIGURE 1) is. internally provided with a thread engaging with thread of the above bushing, so that rotation of ring 17 in either directions defines bushing displacement in either directions and thence a greater or smaller compression of spring operating on head 33 of piston 30.

Head 33 of piston 30 terminates with a substantially semispherical surface 33' lowerly cut by an inclined plane 34 continuing with a horizontal plane 35. Diameter of the semispherical surface 33' is greater than the inner diameter of end 16 of the tubular body 3 and thus finger is retained while being capable of projecting from the same. A transverse pin prevents piston 30 to be rotated about its axis.

In this modification (FIGURE 7), appendix of support 12 has a seating 40 circumferentially shaped and lowerly cut by a secant; in the lower part said appendix 10 also has a triangular notch 41 in order to facilitate the triggered entry of the projecting portion of head 33 of piston 30 within said seating 40, just in which the above projecting portion is normally housed.

From the foregoing it will be apparent that in case of support 12 rotating about axis 5 normal to the ski plane, head 33 of piston 30 slides with'its semispherical surface 33' relative to edges of seating 40; instead, in case of said support 12 rotating about axis 11 normal to the former, i.e., when the boot tip lifts relative to the ski plane, head 33 of piston 30 slides with its inclined plane 34 relative to edges of seating 40.

By providing a suitable slope for the inclined plane 34, it will result that the required stress to cause exit of piston 30 with head 33 thereof from seating 40 is in the first case lower than that required for the second case. As a matter of fact, in the two cases there are two separate forms of resilient restraint following different laws: in the case of the inclined plane, the reaction component of the spring opposing the uncoupling proportionally increase as the total reaction is increased; instead, in the case of the semispherical surface, while the total value of the spring reaction increase as piston is inwardly urged, the component of such reaction, opposing the uncoupling, becomes gradually smaller in relative value.

In addition, the component of the total stress leading to un-coupling remains constant in the case of the inclined plane, whereas, in the case of the semispherical surface, it increases as the edge of port 40 slides along the semispherical surface.

A second modification, intended for solving the safety problem of ski uncoupling by stresses of a different intensity in the vent of twisted and vertical forces, is shown in FIGURES 8, 9 and 10, wherein, in its appendix 10 normal to the ski plane, support 12 is provided with the usual circular bore 26 forming a seating for the projecting cap 4 of the locking ball 4; however, a portion of the lower edge of bore 26 is provided with arim 27 projecting towards ball 4 and semilunarly shaped, the upwardly and outwardly lateral ends 27 of which gradually join with plane of appendix 10 immediately below the horizontal diameter of the bore. From the particular form of this projecting rim 27 it will result that uncoupling of support from the ball in a lateral direction is achieved by a stress which is smaller than that required for uncoupling in a vertical direction, where a maximum value of stress will be required.

More particularly, as seen in FIGURE 8, this third embodiment comprises: a base 1 integral with ski 2; a tubular body 3 containing the adjustable pressure ball 4; the vertical pivot 5; the idle block 6 rocking in the horizontal plane and the support member 12 pivoted at 11 on block 6 by means of fins 9 and transverse pin 11.

At the end opposite to the pivoting end 11, member 12 has a downwardly and at right angle bent appendix 10, thus normal to the ski plane when in closed position. In said position, appendix 10 has a through bore 26 co-axial with ball 4, in which bore the exposed and projecting cap 4' is seated, thereby forming a stop for member 13. Below said bore 26, tangentially to its lower edge and partially concerning also the edge itself there is provided an arcuate deformation of the appendix 10, the convexity of which faces the ball. Said deformation forms a rim 27 being of a semilunar shape and the radius of which is greater than that of bore 26, so that the upwardly and outwardly lateral ends 27' gradually join with the inner face of appendix 10 and terminate below the horizontal diameter of bore 26.

Rim 27 is preferably formed by embossing, it must show the above disclosed features and its maximum pro jection in the lower region of bore 26 has to be designed in relation to the pressure adjustment of ball 4.

It is suitable to note that the objects attained by this improvement take advantage of the principle ensuring a safer operation of the device without its prime cost being notably increased, which makes up a remarkable technical progress carrying out the purpose of ensuring a reaction differential to uncoupling between different stresses the skiers foot is subjected to, i.e., twist stresses and vertically directed stresses. I

What is claimed is:

1. A safety device for ski-boot coupling, comprising, in combination, a base provided with a pivot normal to the ski plane, about which is rockingly mounted a link block passed through by a horizontal pin, at right angles to said pivot and to the ski edges, on which a support member carrying a plate is rockingly mounted through two parallel side fins, the end of said support member remote from the pivot carrying a downwardly turned appendix perpendicular to the ski plane, in which there is formed a bore surrounded by an annular seating of a dissymmetrical section and adapted to accommodate the projecting portion of a small ball under the adjustable resilient action of a spring, the dissymmetrical seating for the ball joint having at least two horizontal diametral regions with a reduced slope, and a lower region with a steep slope.

2. A device according to claim 1, characterized in that the downwardly facing appendix of the plate carried by the support member has on its outer surface a notch for accommodating the boot tip and also two lateral sole fastener fins parallel to the ski plane.

3. A device according to claim 1, characterized in that the rocking axes, respectively, (5) perpendicular to the ski plane and (11) horizontal and perpendicular to the ski sides, about which the support member carrying the plate can rock, are close but do not cross, and in that the horizontal axis (11) is very close to the ski plane.

4. A device according to claim 1, characterized in that the dissymmetrical annular seating suitable to accommodate the projecting portion of the small ball is internally shaped as a substantially semispherical surface having in its region nearer the ski a curvature with a radius smaller than that of the curvatures of the lateral regions in order that exit of the ball in said region is rendered more difficult.

5. A safety device for ski-boot couplin according to claim 1, characterized in that the ball 4 being replaced by a piston (30) and in that the downwardly facing appendix of the support member is in its portion perpendicular to the ski plane provided with a port, within which the head (33) of said piston is adapted to enter by triggering, said head projecting from the substantially cylindrical tubular guide body, also including the adjust ing device for the piston pressure.

6. A device according to claim 5, characterized in that the projecting portion of head (33) of piston (30) is substantially semispherical and lowerly cut by an inclined secant plane, the port within which it enters and formed in the appendix of support (12) being in the shape of a circumference lowerly cut by a secant, whereas shank (31) of the piston is inserted in the axial space of a cylindrical helical spring, an end of which rests against a lug of the piston head, and the other end of which rests against the bottom of the threaded bushing forming part of the adjusting device for the outlet pressure of the piston.

7. A safety device for ski-boot coupling according to claim 1, characterized in that the bore provided in the downwardly facing appendix (10) of the support member (12) is adapted to form the seating for the projecting cap of the locking ball and has on a lower portion of its periphery facing the ball a projecting rim suitable to oppose to exit of the ball in that peripheral portion a greater resistance than in the other portions of said periphery.

8. A device according to claim 7, characterized in that the projecting rim exhibits the ball an inclined plane surface opposing the maximum reaction in the lower region to exit of ball itself, whereas reactions are decreasing from the center line to the lateral ends so as to oppose in the lower region (vertical displacement of the boot) the maximum reaction to exit of the ball and decreasing reactions on the sides (torsional displacements of the boot and thence of the skiers foot).

9. A device according to claim 7, characterized in that the projecting rim, which concerns the lower region of the bore edge, is of a semilunar shape (27) with a radius greater than that of the bore and the upwardly and outwardly lateral ends (27) gradually join with the appendix plane on two points located immediately below the horizontal diameter of the bore.

10. A device according to claim '7, characterized in that the maximum projecting point of rim (27) is located on the extension of the vertical diameter of the bore.

11. A device according to claim 7, characterized in that the projecting arcuate rim (27) located below the lower half of bore (26), within which the projecting spherical cap (4') accomodates, is formed by an embossing in the wall of the vertical appendix (10) of the supporting member (12) below the bore (26).

References Cited UNITED STATES PATENTS 3,186,727 6/1965 H-atlapa 28011.35 3,222,079 12/ 1965 Marker 280-1135 3,244,431 4/1966 Hatlapa 280l1.35

BENJAMIN HERSH, Primary Examiner. J. H. BRANNEN, Assistant Examiner. 

1. A SAFETY DEVICE FOR SKI-BOOT COUPLING, COMPRISING, IN COMBINATION, A BASE PROVIDED WITH A PIVOT NORMAL TO THE SKI PLANE, ABOUT WHICH IS ROCKINGLY MOUNTED A LINK BLOCK PASSED THROUGH BY A HORIZONTAL PIN, AT RIGHT ANGLES TO SAID PIVOT AND TO THE SKI EDGES, ON WHICH A SUPPORT MEMBER CARRYING A PLATE IS ROCKINGLY MOUNTED THROUGH TWO PARALLEL SIDE FINS, THE END OF SAID SUPPORT MEMBER REMOTE FROM THE PIVOT CARRYING A DOWNWARDLY TURNED APPENDIX PERPENDICULAR TO THE SKI PLANE, IN WHICH THERE IS FORMED A BORE SURROUNDED BY AN ANNULAR SEATING OF A DISSYMMETRICAL SECTION AND ADAPTED TO ACCOMMODATE THE PROJECTING PORTION OF A SMALL BALL UNDER THE ADJUSTABLE RESILIENT ACTION OF A SPRING, THE DISSYMMETRICAL SEATING FOR THE BALL JOINT HAVING AT LEAST TWO HORIZONTAL DIAMETRAL REGIONS WITH A REDUCED SLOPE, AND A LOWER REGION WITH A STEEP SLOPE. 